1. Field of the Invention
This invention generally relates to acoustical loudspeakers and more particularly to acoustical loudspeakers with improved bass response.
2. Description of Related Art
My U.S. Pat. No. 4,595,801 discloses a dual cone loudspeaker with a primary speaker cone similar in function to a conventional dynamic loudspeaker mounted on a frame with a magnet structure. A secondary speaker cone mounts to a subframe on the back of the magnet structure and connects to the primary speaker cone through a rigid coupling device so the primary and secondary speaker cones move in unison. Sound waves from the secondary speaker cone travel through an orifice in a center pole piece of the magnet structure and through a hole in the center of the primary speaker cone radiating in the same direction as sound waves from the primary speaker cone. Consequently for a given excursion of the primary speaker cone my dual cone structure generates a sound having a greater sound volume than the primary cone alone by virtue of the simultaneous excursions of both the primary and secondary speaker cones that move a greater air volume for a given speaker cone displacement.
More specifically, the speaker disclosed in my patent includes a primary speaker cone with a frustoconical form with the center removed that attaches to a bobbin that carries a voice coil. The rigid coupling device includes a center link with radial spokes. The radially outer end of each spoke attaches directly to the secondary speaker cone at the voice coil bobbin. However, it is difficult to attach these outer ends of the radial spokes to the speaker cone or bobbin without distorting the voice coil. Moreover, adhesive or other techniques for bonding the ends of the radial spokes to the bobbin are subject to fatigue and ultimate failure. Stress concentrations at attachment points tend to force the bobbin out of round in operation contributing to a short life span for the speaker. It has also been found that this speaker is limited to operation at lower frequencies as a bass speaker. It would be helpful if the useful frequency range could be is extended to higher frequencies.
Therefore it is an object of this invention to provide a dual cone loudspeaker with an improved linkage between the primary and secondary speaker cones.
Another object of this invention is to provide a coupled dual cone loudspeaker with a reliable construction.
Still another object of this invention is to provide improved linkage that enables a coupled dual cone loudspeaker to operate over an extended frequency range.
Yet another object of this invention is to provide a coupled dual cone loudspeaker that is easy to manufacture.
Yet still another object of this invention is to provide a coupled dual cone loudspeaker that is capable of broadcasting a wider range of frequencies with fidelity.
Still yet another object of this invention is to provide a coupled dual cone loudspeaker that can radiate a wide range of frequencies applied to a single voice coil.
Yet still another object of this invention is to provide a coupled dual cone loudspeaker capable of producing high frequency radiation independently of signals applied to a voice coil for a primary speaker cone.
In accordance with one aspect of this invention a coupled dual cone loudspeaker includes a first speaker cone resiliently suspended from a frame. A voice coil responds to first signals for displacing the first speaker cone relative to the frame. A second speaker cone is resiliently suspended from the frame and spaced from the first speaker cone. A ring attaches to the first speaker cone and an open support structure connects the ring to the second speaker cone whereby motion of the first speaker cone produces corresponding motion of the second speaker cone.
In accordance with another aspect of this invention, a dual-cone loudspeaker includes a loudspeaker frame, a first speaker cone resiliently suspended from the frame, voice coil for displacing the first speaker cone and a second speaker cone resiliently suspended from the frame and spaced from the first speaker cone. A link interconnects the first and second speaker cones whereby motion of the first speaker cone produce.,5 a corresponding motion of the second speaker cone. The loudspeaker additionally includes a high-frequency radiating structure attached to the link for producing high-frequency output signals in response to high-frequency signals applied to the voice coil.
In accordance with still another aspect of this invention, a dual-cone loudspeaker comprises a loudspeaker frame with a permanent magnet for defining a magnetic gap, a first speaker cone resiliently suspended from the frame, a second speaker cone resiliently suspended from the frame and spaced from the first speaker cone and a voice coil for being energized by an audio signal in electrical form. A cylindrical structure located in the magnetic field gap carries the voice coil and attaches to the first speaker cone whereby low frequency signals applied to the voice coil produce corresponding motion of the cylindrical structure. An open support structure formed centrally of the cylindrical structure includes a rigid link that connects to the second speaker cone whereby low frequency motion of the first speaker cone produces a corresponding motion of the second speaker cone.
In accordance with still another aspect of this invention, a dual-cone loudspeaker includes a loudspeaker frame with a permanent magnet means for defining a magnetic gap, a first speaker cone resiliently suspended from the frame and a second annular speaker cone resiliently suspended from said frame and spaced from said first speaker cone. A voice coil, energized by an audio signal in electrical form, is formed on a rigid cylindrical structure located in the magnetic field gap. The cylindrical structure is a component of a rigid link that interconnects the first and second speaker cones and that includes a rigid circular structure positioned in the opening through the second speaker structure and resiliently attached thereto about the periphery of the rigid circular structure and that includes a rigid element interconnecting the rigid cylindrical structure and the rigid circular structure. Low frequency signals applied to the voice coil produce corresponding motion of the first and second speaker cones and high frequency signals applied to the voice coil produce corresponding motion of the rigid circular structure.